OFFSET
0,2
COMMENTS
Inspired by Fig. 1 of Cobeli and Zaharescu.
LINKS
N. J. A. Sloane, Table of n, a(n) for n = 0..2000
C. Cobeli and A. Zaharescu, Promenade around Pascal Triangle-Number Motives, Bull. Math. Soc. Sci. Math. Roumanie, Tome 56(104) No. 1, 2013, 73-98.
FORMULA
Stirling's formula shows that a(n) ~ n^2/(2 log 10) = 0.217... n^2.
EXAMPLE
"1 6 15 20 15 6 1" contains 16 characters, so a(6) = 16.
MAPLE
lis:=[];
M:=100;
f1:=n->[seq(binomial(n, k), k=0..n)];
for n from 0 to M do
t1:=f1(n);
t2:=convert(t1, string);
t3:=length(t2)-2-n;
lis:=[op(lis), t3];
od:
[seq(lis[i], i=1..M)];
PROG
(PARI) a(n) = n + sum(k=0, n, #digits(binomial(n, k))); \\ Michel Marcus, Aug 29 2015
CROSSREFS
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Feb 16 2013
STATUS
approved